The solution to this error is obvious: we must put the correct email address in the “to” field or in the “CC” and “BCC” fields if we are using them. In this way, we can send the email and it will reach the recipient correctly and without problems.
We are on spam lists
If from our email account we have sent many emails indiscriminately, it is very possible that many recipients have classified us as “spam”, and we will have problems when sending the emails because the recipients will not receive them, but will remain directly in the anti-spam filter of the email provider. If we use Gmail or Outlook accounts and many recipients classify us as spam, it is very likely that we will have a notice from the provider itself indicating the problem, and that we will stop sending emails, and it may even happen that our account is directly blocked.
In this case, the solution to the error is to not send emails indiscriminately, if we have already done so, it will be difficult to have our account “clean” again, so it is best to open a new email account to avoid these problems . However, most providers will always provide us with solutions to avoid closing the account and having to open a new one.
Banned public IP address
If we are sending the email from an IP address that is classified as spam or malicious, it is possible that we will have problems when connecting with the mail provider, because it will detect that you are sending an email through an IP classified as spam. These types of problems are usually found when we use email accounts to receive notifications from operating systems, routers, monitoring program notifications, etc. It is not very common to find this failure on a user’s PC or smartphone.
The solution to this problem is simple, we have to change the public IP address of origin of the email, we can use a VPN service that is the simplest. For example, you could use WARP from Cloudflare which is a totally free VPN and it works really well, this way you won’t have any problems sending this email.
Attach prohibited files
If you are trying to attach files that are prohibited by the origin or recipient email provider, we will have problems getting the email to arrive. First we must highlight problems with our email provider, in the case of Gmail or Outlook we will not be able to attach .EXE executable files and other extensions, the same thing happens if we compress this .EXE into a .ZIP file, it will not allow us to attach it and We will not be able to send the email directly. In the event that we use an email provider that does allow us to attach this type of file, then it is likely that the problem is found in the recipient’s email provider, since it surely does not accept this type of file.
If you need to send “prohibited files”, then you will have to make use of cloud storage services like Google Drive, OneDrive, Dropbox, pCloud, use a NAS server to send a link to it to download the file, and even create a container encrypted with VeraCrypt to send it as an email attachment, since email providers will not be able to read them.
oversized attachments
Closely related to the previous point is that of attaching files that are too large. The main email providers allow you to attach a maximum of 25MB for each email, if we exceed this size we will not be able to send it, and we will have to use the different cloud storage services. Also, if we send a 25MB attachment but the recipient only has 20MB available to receive emails, we will receive an error indicating that the destination has a full mailbox. It is not really full, but our mail does not fit so the error is the same.
The solution is quite simple, send an email without the attached file, but with a link to a cloud storage service where you can download it without problems and whenever you want. In this way, the email will occupy a few KB of data because only the text and the link to the download will be sent.
Sending email to many recipients
Email providers have a limitation of emails sent per day, and also to how many recipients we have sent a specific email. This is done to mitigate possible SPAM originating from your email accounts. If we are very active in email and send an email to dozens of recipients, it is possible that you have problems of this type, due to the limitations imposed by email services.
Solving this problem is not easy if you are making a legitimate use, because you are exceeding the policies of the email provider. This provider may have email payment plans where these limits are higher or even have no limit at all.
The error is in the recipient’s account
In the event that the error is caused by the recipient’s account, we will not be able to do anything to correct it, but we may be able to notify the recipient through a form of communication other than email.
Mailbox full
The main problem that we find in the recipient is that of full mail. If you have a very low-capacity email inbox, it may have already reached that capacity and is not allowing you to receive any more new emails. Some providers allow up to 110% of the size of the mailbox to be exceeded, to avoid problems with not receiving new emails, but this margin will end and the recipient will have to free up storage space in the mailbox.
With this error you won’t be able to do anything, but what the recipient can do is free up space in the email inbox so as not to have problems when receiving new emails. In this error, we will not only have problems receiving emails with attachments, but also the emails themselves that occupy only a few KB of information.
The email account has been canceled
If we have tried to send an email to a correct address, but the recipient has unsubscribed for some reason, we will not be able to do anything to try to send the email. In this case, the problem is because the destination has canceled the email address, and we will have to find another way to communicate with that person.
This error would be exactly the same if we have sent an email to an incorrect address that does not exist, because in fact, this email address no longer exists, so it will be available for registration by user user.
You have classified us as spam
If we have sent an email correctly and the destination has classified us as spam on some occasion, our emails will not appear in your email inbox, but will appear in the junk or spam section, so we must take it into account. In this case the problem is not ours, it will not give us any error but the recipient will find the email in the SPAM tray.
As you have seen, there are a large number of reasons why we cannot send an email correctly to the recipient, in some cases the problem is ours and we can solve it, but in other cases the problem is the recipient’s and not we can do anything to fix it.